Electric storage batteries



INI/ENTOR.

ATTORNEYS 5 Sheets-Sheet l H. W. KOREN ELECTRIC STORAGE BATTERIES l! if i/ Filed March 21,

' May 10, 1955 May 10, 1955 H. w. KOREN 2,708,213

. ELECTRIC STORAGE BATTERIES Filed March 2l, 1952 5 Sheets-Sheet 2 BY M Mk 5,42@

HORNEYS May 1o, 1955 Filed March 21, 1952 H. W. KOREN ELECTRIC STORAGE BATTERIES A:' sheets-sheet :s

I DHI l l" May 10, 1955 H w, KOREN 2,708,213

ELECTRIC STORAGE BATTERIES Filed March 2l, V1952 5 sheets-sheer 4` E JIA- El/'1.5i

BY M@ TTORNE YS May 10, 1955 H. w. KoREN 2,708,213

ELECTRIC STORAGE BATTERIES Filed March 21, 1952 5 snee'ts-sneet 5 United States Patent ELECTRIC STORAGE BATTERIES Heiman W. Koren, Bronx, N. Y., assigner to Sonotone. Corporation, Elmsford, N. Y., a corporation of New? York Application March 21, 1952, Serial N0. 277,844

5 Claims. (Cl. 136-166) This invention relates to electric storage batterie and their production, and more particularly,to alkaline storage batteries which Vare known as nickel-cadmium.. storage batteries. It was long known that for be'st f results such nickel-cadmium batteries should operate with porous electrode plates of sintered nickel powder particles having the pores loaded with the active materals for the positive and negative electrodes, respecf tively. However,'in the past, the processes used in,

forming sintered l,activated electrode plates for such nickel-cadmium batteries were unsatisfactory and the resulting plates varied widely in their characteristics; and a great percentage of nickel-cadmium batteries.

produced with prior art sintered plates became defective in the initial stage of their operation. l

`Among the objects of the invention are methods by.

which the sintered electrode plates for such nickel-l cadmium batteries may be produced in a way that makes it possible to obtain highly effective sintered electrode plates for such batteries of consistent quality and chati-r acteristics on a large scale production basis.. i Among the objects of the invention are alsosuperior 'sintered electrode plates for such batteries which elim-l inate the diiculties encountered with prior art elec;

trode plates of this type.

, 1t is also among the objects of the invention to pro-` exempliiications thereof, reference being had to the 'accompanying drawings, wherein Fig. l is a vertical sectional view of an assembled battery cell made inaccordance with the invention; V`Fig lA is a detail side view of the central portion of the top wall; Y

Fig. 2 is a cross-sectional view along line 2--2 of Fig. 1;

Fig. 3 is aA top elevational view of the battery'cell of Fig. l; y

Fig. 4 is a cross-sectional view of a portion of a large sintered sheet formation representing the-lirst stage in forming battery electrode plates of the invention;

Fig. 5 is a plan lview showing a portion of the same large sintered sheet formation in a subsequent forming stage;

Fig. 6Ais a plan view similar to Fig. 5 of an individual battery electrode plate formed by cutting the sheet formation of Fig. l; l

Y Fig. 7 is' a view similar to Fig. 6 of the same electrode plate in a later forming stage with the electrode tab aixed thereto;

Fig. 8 is a cross-sectional view along line 8-8 of Fig. 7;

Fig. 8A is a view similar to Fig. 8 showing a modi,- fied form of plate;

Fig. 9 is a plan view of a sub-assembly of positive and negative electrode plates and the interposed separator formations of such battery joining the electrode leads of the sub-assembly to the battery terminals of the cell housing;

Fig. l0 is a cross-sectional view along line lll-10 of Fig. 9 with some of the parts shown exaggerated for the sake of clarity; I

Fig. l1 is a cross-sectional view along line 11--11 of Fig. 9, with some of the parts shown exaggerated;

Figs. ll-A, ll-B and ll-C are curve diagrams giving typical operating characteristics of a battery of the invention;

. Fig. l2 is a top view of one form of a multicell battery formed of battery cells of the type shown in Figs. 1 to 3;

Fig. 13 is a side view of the battery of Fig. 12; and

Fig. 13-A is a cross-sectional view of a portion of the battery of Fig. 12, along line 13-A, 13-A of Fig. 12.

The principles underlying the features of the invention disclosed herein will be explained by reference t0 one practical form of a battery c'ell shown in Figs. l to 3, and generally designated 10. The battery cell 10 comprises a at casing having two extended side walls 11 with adjoining two narrow side walls 12 and a bottom wall 13, the casing space being enclosed at the top by a top wall 15. The housing walls 11 to 13 and 15 areall made of a suitable alkali-resistant material. Suitable resin materials for this purpose are the nylons, polyethylene terephthalate (Daeron), acrylonitrile, polystyrene, polyvinyl chloride and like synthetic resins which are resistant to lalkali solutions.

Within the top wall 15 are mounted, and are held xed and sealed therethrough with a Huid-tight seal, two metallic terminal members 21l of opposite polarity providing terminal connections to lthe opposite polarity battery plates held on the electrode assembly generally designated 30 within the interior of the casing 11. Each of the two terminal members 21 is made in the form of a metal shank, passing through an opening within the insulating top wall 15 and having on its inner side an enlarged head 22 helduseated across a sealing washer, 23, of alkali resistant rubber material, such asV neoprene, against the overlying seating surface of the top wall bordering the opening thereof. The shank head v22 is held clamped to its seat by a sealing nut 24 threadedly engaging the upper threaded portion of the terminal shank'rnember 21 and clamped against the underlying seating'surface of the top wall 15 to form a liquid-tight seal therewith. If desired, an additional rubber-like' sealing washer 23-1 may be interposed between the sealing nut 24 and the underlying seating surface of the top wall 15 of the housing.

The inner head 22 of each terminal member is provided with downwardly extending ear members 26 to which are a'ixed, as by welding, the upper ends of a superposed opposite polarity array of strip-like electrode leads or tabs 31, 32 of the battery assembly 30. The two terminal members 21 are made of alkali-resistant rnetal, such as nickel.

The inner faces of the large side walls 11 of the cell casing are provided with short rib projections 11-1 for holding Athe large side surfaces of the battery assembly 30 slightly spaced, such as by a gap spacing of about .O20 to .040 inch, from the inner walls of the casing. Similarly, the inwardly facing side of the bottom casing wall 13 is provided at its opposite narrow end regions with the raised ledge portions 13-1 for holding the bottom ityelectrodes increases.

Yedges or-the electrode assembly 30 at a small gap spvac- I" ing, such as .020 to .040 inch, above .the.surfaceV of-the----Y `1 bottom `wall 13.

The battery assembly 30 is permeated by and `held immersed `within a liquid body of an electrolyte shown extending up to a level 41 which is higher than the upper level of the-electrode assembly 30. "l'he electrolyte'lol such nickel-cadmium batteries usually consists of a 20 to -35% (by weight) 'solution of potassium hydroxide KOHin water. 'Excellent results arey obtainedlwith 1a 30% solution of potassium hydroxide as the electrolyte'; The well known principles ofv operationf'ofV l'nickelcadmium batteries having positive electrodes'of nickelous hydroxide particles lNi(OH)3 vand-negative electrodes ofcadmiumhydroxide vparticles Cd(O'H')3 immersed in an electrolyte consisting of a solutionfof'potassium"l hy'.v dioxide are believed at presentf'ftobe lsubstantially as fol- 1OWs:. .L f' "When fully charged, the-- active positive electrode' ma t'erial consists "of nickelic'hydroxideand the active nega;y tive electrode material consists of cadmium. During "the discharge, the active material` of the ypositive electrode tends to reach a lower energy level involving la reductiony ofits active nickelic hydroxide material to the lower nickelous hydroxide 2Ni(OH)2 and the releasing of negatively charged hydroxyl ions ywliile the negative electrode isv oxidized to form cadmium hydroxide Cd(OHf)2 and/ or eadmiumoxide and giverup electrons tothe-external circuit. In charging such cell, chemical Vchanges take place at the positive electrodeinvolving oxidation of its nick; elous ,hydroxidel material and/or'the' release of; oxygen while the activel electrode material of, the negative elecj tr'ode, to wit,rt`he cadmiumhydroxide and/or cadmium oxide, undergo'a chemical change' which involvesthe Vre'ductionof the,` cadmium. hydroxide and/or ,cadmium oxideto purev cadmium and the'release of hydrogen: Aci

cordingly, `gas will developfin'the cell during thejcharg-- ing process while .the voltage between `the opposite polar-y v One phase of the present invention volves la novel method and processes for the manufacture of sintered activev electrode plates for such nickel-cadmiunibatteries which will be now explained Vin connection with Figs.y 4 to8.` In accordance with .the invention, the electrode plates forl'nickel-cadmium batteriesare formed,` by producing' them out vof lar'gesi'nt'ered sheet 'formation' of nickel particles' loadedv and treated to embody in them `the proper amount of the respective positive vandV negative active jelec; trode material, the so-treated Vand formed largefsheet formationbeing Vthereafter'cut into properly formed'elec trode plate sections of the required, size out of which the electrode assemblyo the batteryl cell visformed.

- In general,v Athe process of kformingthe, positivA negative electrode'platesv out of largeV sheet formations in" accordancewith the invention, involves the' following series of steps. Y f Y i V1st,' a thin` grid, reticulated sheet ora layer of; gauze o'f metallic nickel is placed between two layers of fine Ynickel powder within a.suitable refractory carrierolj boat and sintered atan elevated temperature so as to form a self-supporting sheet formation of sintered nickel p arf ticlesVv having embedded in its interior .the-.thin backing grid orgauzeiof metallic nickel which strengthensV and backs up the sheet 'formatiori.',v l '4 2nd, t he f'large sheet formation produced in the ls'ft step is then placed in Va'die arranged to compact thereinl crossyvise extending narrowv separation zones wherein` 'the having thin compacted subdivision zones is then further u sfintered or resint'ered at an elevated temperatu're in agprotective atmosphere for increasing. the bondbetween' particles are compresed 'veryhhighvdensitynd metalv particles resulting in sheet formations consisting ofrasheetvsections having 80 to about 85% porosity separated by highly compacted narrow separation zones of only 5 to 2% porosity or 95% to 98% density.

4th, depending on the width, one, two or more processing tabs of nickel sheet material are welded to spaced portions along one edge of `each, sheet formation which has been previously compacted to ,substantiallyl the thickness of its backing screen or'grid; 5th,an array 0f; Sdllargey Sheet formations-s :then loaded rwith the potentially active material, to win-assolution of nickel nitrate for the positive electrode sheet-formationsI and a solution of cadmium nitrate forv the negative electrode sheet formations.

6th, thereafter,theloadedarraysof; sheets for the respective electrodes are activated by placing them inV a strong alkali solution of either sodium or potassium hydroxiderand subjecting them to a cathodic electrolytic -V process Wherebythe'nickel nitrate andcadmium 'nitrate 3th, the-'washed sheet formations are'then'brushed for' otherwise treated `while wet, asl with'a 'sprayg'rto"'rem'cn/jel from'theirsurfac'es any encrustationsV `of active material andany loose particles .present'thereom f "'lSteps 5th to18th are repeated inlsenuencea number' 'of times until ali'she'et formations have been properly'loaded with the z ictivseelectrode materials. j;

9th,' fat'terl tying,v a rays ofA so-.prfeparedl sheet flrvmav tions, of" Valternate polarity, fwith interposed separators',

charging cycles followerdhy a discharge'.

Yare hen placed in a' forming bath and given a number of 10th, 'after properl' loading, activating and r'forming the sheet Afr )rmationsare,'af/ter inst-washing, thickness# sized,ir/,hilehwet', asfby compaeting in sizing press to" bring their activeflargeareas to the desired thickness. A' '11th, Vthe'sheetV formations are then 'stackedjflatpud llattened under aweight, and the weighted" stacqkfi'sjl dried. "12th, thelarge sheet formations 'arefthereafterfcut u along the."` highly Yconmactedjthiny s 'eparation'vzones 'and separated' 'into'. sheet sections', each' of the size 'ofA the lde-k siredbattery electrode plate., j

' 'l3th,` the edges4 of he' 'electrode Aplate sections so formed by cutting the .large sheet formationsfarefthen coated with cementitio'usjrnaterial, for instance'gfa plastic 'or' syntheticresin coating materialfto bind 4into position any particles which may have'been 'loosened'by theflcutg ting operation and. to"'eover any sharp edges "of'tli back; ing screen formed`i exposed ther' uttingvoperation. 14th, electrode lead tabs' are then welded'to cgmpncvted thin compacted' corner portions lof the individualfelectrode plate sections; thereby completing the individualelectrode plates, whereupon they are ready fon--a'sfserrblyl'into battery electrode lsub-assemblies,l 'such as shown Vat' 3Q in Fig. l. l:'I'he'individu'al steps of the .process of .theinyention `for forming the opposite polarity plate of a nickel-cadmium battery in accordancefwith the invention inthe'manhe outlined above will-.nombre,desctibdfin moredetail In the 1st s tenjpure .nickel .Pon/dersie formed., .mee

@come 1a Such reticulated orv perforated nickel backing sheet may also be formed by an-electro-deposition process. Where wire gauze' is used, its electrical conductivity, may be im4 proved b y electro-depositing thereon in an felectroplating bath a thin stratum of nickel. Dependingb'on the thickness of fthe final electrode plates, metal sheets or wire mesh formed of wire having smaller or greater thickness may be used. Thus, by way of example, L'very effective electrode plates .025 inch thick, may be produced with a backinggsheet of a nickel wire mesh of 20 wires per inch in cross-wise directions, each wire having afthickness of .007'inch, such mesh being conventionally designated 20 :t 201C ".007 mesh. Similarly, very effective electrode plates .015,0 inch thick may be produced with a backing sheet of nickel wire mesh 16 X I6 x .0.12. r,

By wayof example, for producing sintered electrode plate sheets of the invention having a' thickness of .025 inch, a backing gauze of nickel wire 20 xvlZhO x .007 is placed between twolayersof fine nickel powder within a suitablef mold of graphite, for instance. The powder formations are then sintered in a furnace at an elevated temperature in the range of 800 to 10009, C. within a protectivefatmosphere of cracked ammonia-for l0 to l5 minutes u'n'til the nickel particles are iirmly'sint'ered to each other 'and'to the backing sheet and form therewith a self-supporting sintered powder sheet formation of about .02;inch thick with the sintered powder body eX- hibiting about 75 to 90% porosity. As the nickel powder layeils shrink in sintering, suitable allowance is made in dimensioning the two powder layers deposited in the mold preparatoryto the sintering operation. Good results arellobtained with sinteriug at 900 tor925 C. for l2 to l,- inutes, yielding sintered nickel powder sheet formations vof about 82 to 86% porosity.

Fig. a cross-sectional view of a portion of soformed ered nickel powder sheet formation 51 about .025 to .030 inch thick consisting of sinterednickel powder particles in which is embedded a nickel ivire mesh gauze Srwherein the sintered nickel powder'; body has a porosity'o'flgS?. to 86% and is used for forming .electrode plates of kthe invention. The pores or interstices between the sintered nickel powder particles are of'inicroscopic din'iensioi'is.` v

In the 2nd step, the sintered nickel sheet formation 51 is subjected to the compacting treatment in which it is placed within a compacting die for formingrfalong the large sheet formation 51 cross-wise extending narrow highly-compacted separation zones along which the sheet formation is subsequently cut into the separate electrode plate sections.V Fig. 5 is a plan view showing the general configuration of a sheet formation of Fig. 4 after it is given such compacting treatment. The compacted sheet formation 54 shown in Fig. 5 has cross-wise extending narrow-separation zones 55 about 1A@ inch thick, and also narrow edge -zones 57, about /g inch thick which are highlyvcompacted to substantially the thickness of the screen mesh 5,3 embedded therein. On the other hand, themajor area of each section 58 bordered by the thin compacted -zonest55 and 57 isA not compacted so that it retains the desired porosity and may be formed into the effective electrodes in the manner described hereinafter.

One of the compacted edge zones such as the upper edge 'zoue 517-1 of the sheet formation (Fig. 5) is made somewhat wider, about 1/4 to 1/2 inch and is used to provide processing connections thereto. Y

The compacting die is so shaped as tol format the corner of each plate section 58 a compacted corner region 59 serving a sthe electrode junction of each electrode plate section 58.` To simplify the compacting operation, the compacting die is so designed as to form the compacted corner terminal regions 59 on'four adjoining corners offour adjoining electrode sections 58 of the sheet formation 54, as indicated in Fig. 5. Fig. 8 shows in cross-section, the generalV configuration of the main surface regionof each electrode plate section 5.8 and ofthe compacted-separation zones or edge regions 55 thereofi Depending on the requirements, such compactediermina'i region 59 may be formed along another portion of Ythe edge regions of the individual plate section 58, of lsuch sheet formation 54 (Fig. 5). ii l f In the neit" 3rd step, the compacted section'alized large sheet formation 54 obtained is subjected to'ah 'additional or sintering treatment. In this additional sintering treatment, an array of such large compacted sheetiformations is maintained at an elevated temperature within a similar oxidation suppressing protective atmosphere'for causing the' particles'of the sintered sheet to be very firmly and closely bound to each other. It has been found desirable to eiect the resintering treatment at a lower temperature and for a shorter period than the original sintering, such as about 650 to 950 C. for about 7 to 2 minutes. In producing plates about .025 to .050 inch thick, good re# sult's are obtained by resinteringv at about 870 C. for about 3 minutes. v f1;

In the neit 4th step, processing tabs 61 of nickel sheet material aref attached, as by welding, to spaced portions of the somewhat wider compacted edge regions 57-41 of each large sheet formation 54 (Fig. 5) for'use' in the subsequent Itreatment steps. Y

In the next 5th step, the loading treatment, an array of similary s heet formations 54, such as sliown in Fig. 5, are placed in a solution of either nickel nitrateA or cadmium nitrate, for loading their microscopic pores therewith preparatory to the activating treatment in which they are formed either into positive or negative electrode plates, respectively. The porous sheet formation for'the positive electrode is impregnated with a solution of nickel nitrate Ni(NOa)2.6H2G with a slight exlcfess of nitric acid. TheV porous sheet formation for the negative plates is impregnated with a solution of cadz'iiium nitrate Cd(NO3)24H2O. A suitable impregnatingsolutioti of nickel nitrate is one which is nearly saturated at room' temperature, of 20 to 30 C. and a suitable' solution of cadmium nitrate is one which is similarly nearly saturated at such room temperature. Good results are obtained with a nickel nitrate solution having a specific gravity of 1.6 and a cadmium nitrate solution havir'ifg a specic gravity of 1.8 at room temperature. In this .loading treat# ment, the sintered compacted porous sheet formations 54 are placed in a vessel, and after evacuation of the vessel, the nitrate' solution is introduced into the vessel for impregnating and loading the pores of the extended elec# trode area sections 58 of each sheet formation 54 with the proper nitrate solution.

In the next 6th treatment step, the loadedsheet formations 54 for the positive or negative electrode plates'are activated by a cathodic electrolytic process within a heated bath of an alkali solution of either sodium or potassium hydroxide'for converting the nickel nitrate and cadmium nitrate loaded into 'the microscopic pores fof the plate sections into the desired active positive or negative electrode `material, respectively. In the positive 'electrode plate sections of thesheet'formationA 54 the nickel nitrate loaded into its pores is' converted by the electrolysis into nickel hydroxide retched within the pores of the plate.l In 'the negative'electrode sections of the sheet formation 54 the cadmium nitrate loaded into its pores s converted by the electrolysis into cadmium hydroxide, and some of the'hydroxide is reduced into cadmium'. The electrolizing bath may be formed of a l5 to 25% sollttion of either sodium or potassium hydroxide and itis kept near the boiling point. By way of example, good results are obtained with va bath formed of a 20% solution of sodium hydroxide maintained near its boiling point at about to 110 C. For electrode plates .0.2510 .05()v inch, the electrolyzing current may be about'l/z to 3 amperes per square inch of sheet formation, and it may be greater or larger. Good results are obtained bytreat#v ing such plates with an electrolyzing current of 2.5 aniperes per vsquare inch of sheet formation, y i 'I In the washing treatment, or step 7, each forma- Ygtrpo'res of the sheet formations;

.sheet V electrode immersed in theelectrolyte about 'L5 5to-fle? emmener. Saltare in ehftor the-positive washed sheet fonnationlias e pH .of 7 .0.

albe-Washing treatment is, followed.. .with abrus'i'ns treetmentLof stem-8 for removing .from the preyiously Y treated Sheet formations surface. ericrustationsfonnedby the loadiilsand electrolysis treatmentsand any.- loose par;

t'ielesl loosened or otherwise present .o r. formedeen me heet.. formetions v54.- 1 To.- this. endl the .exterior @tithe washed .sheehformatioo ,is brushedsyhile. wetv with a brush having Suitablebristlessueh as nylon orPolystyrol.JeJ

idippedin ionized .watersA Alternativelybit may. .be sprayed with@ forceful spray ofionized water,v and; such spraying may be combinedwith the brushing.; l The syashedandjso brushed sheet formations are then dried, ,f aindriedn therairof an oven heatedto 8033 lllliil'dl'Y-r.

For eifective results, it has been found'essentialtoiimit duration of each electrolysis Y activation "treatment to a relatively short time, and to subject each sheet; for ma tionpto repeated vsequences of loadingLactivating, washing,

brushingrand drying'treatments several times untiLthe properarnount -of active positive and negative electrode materialfhas beenv deposited in the microscopic crevices By wayofexample, in forming sinteredr'elelctrode:

.42025 to .QSQinch thick,l -good Vresults areobtained-by Elimit; y

ing Ieach electrolysis `activation treatment-to about 1,5 to Zinnnuteis land repeating four to tive. timessimilewe: queoees ofloadinfs, elleetrolySiS-aetiyatins,washing, bras. ingand vdrying 'treatments to each. sheet-formatiollgllu it; showsthe proper gain oiactive'rnaterialby` decreasing the originel porosityof'il to 86 77' ot-the sinteredpowder body of thehshefetihfz 'ons to a porosity of' abou 4 to 6.5% or! more Specifically .toabout- 50 to 60%.: -1 a'. i By )vaylof example, ineach electrolyzingtreatment of each repeated treatment sequence, )Y good- -results fare fobtained with'the electrolysis carried on with a direct. cur; ilizingragzyessel of ,nickel for y,holding the sodium hydro'ide y solution constituting theyelectrolytic bath and carrying v on the electrolysis withacurrent whichat the start develops about oneyoltbetweeofheyesseliand the f In teach. cycle. the electrolysis. is carried envier .ebeiltrls t0.- 21.5. minutes until the voltage between thevessel v. ar1d theinf i7 nietsed c'sheet formation increases toQabout 1,-8. tox 2 volts. t Elway of example, for Sheet z.formations having elec:

Ytrodefpla'te sections 41/2 Ainchessqggare and .Q25 finch thiclgeach electrode section-had afp/eight ,oftabout 72 grams'beforefbeing'subjectedto the s eries of loadingand activating sequences of the type described above. ;Aier completing four .sequences of loading and activating tteatmeafseearried out in the ymolierdeseiibedsaboi/e, the properly. activated positiveplate section showedja weight gain `of 6f5 to 7.5. v grams, and -each properly acti; yfated' ljlegative,plateg section .showed Vanfeightgain .of l l.5 to l14 grams.- With the originally sintered plates haying a porosity of' 85%, the repeatedsequences of activating treatments Vreduce thus the porosity of Vthe activated plates to about 50.to 60% lor a weight gain-of assegnista plates;

Pltesf slid 'a Weight sein-@ghost 24.6: te i12. .grams lyzed d 'sized sheet 'fo' chargipgf and 'c dischargin g cycles.- By -way=- of.; example; withsheetformations .O25 inchthickpgoodgresult's are obtained if they are formed with; the ,following seriesof three. forming cycleszy' y "5;

A rst charging period Yof l3() hours atA '.04-5f-ampfere`- per square inch followed by a 'dischargeat. .065 ampere per` square V,inch until the voltage per cell -drops .foal volt; followed by. Y l aj-'i A second charging period loff '-1.0 hours ;at.f,065 .ampere perV square 'inch followed by. the Same ,-discharge ias in the'liirst cycle; followed by :Si i i A.; third and -tinal charging; period of 7 Jhoui's1at 'ithe samera-te as in the second icycle followed byth'e'" same llisharge.. i f g:

The sintered nickelpowder sheet formations produced by the lst sintering step described.heneinbefore; gives sintered powder. vparticle sheets lofmiekelivarying in;thick nesslbyzabout 110%.v In addition, th e seriesof lo'ad ing,factiyating andforming treatments, .including the re peated v loading and electrolyfzing:.seqeneeseiofV thef v type describedfabove, resultsgin a growthof he .thick'ness'of the 'treatedv sheet formations.

O'nV the otherhand, it is desirable-that the battery electrode assemblies of opposite-polarity havingli'afvrequiredfnurnber" of electrode plates; shouldebe 'generally of the same thickness.V For this reason,. it is important that the individual-electrode plate -sheetglat leastfeac'h group of sheets ofthe same polarity'fshould likewise be of substantiallythesame thickness. -54 :7,1 'f iInac'cordance with. a phase offthefinvention disclosed herein, all electrode plates: of the same'v polarity/ fare givenl substantially. the. samethicknessab'y :subjecting them, in the next treatment step-9, to .a".tl 1 ickness sizing wheie it is subjected#tori-relatively high Icmpcting sures'uch as 2-5001tov5000'p11s. i.-- (poundsperjsqure inc-h') a"for: bringing down ory compacting allfactivated sheet formations-or lelectrode plates'toiisubstantially the same uniform =th`ickness. l ""Ifhis lsizing Atreatment may be applied'towthe. sheet formations before subjecting therri to ithefelctrolytic 'forming treatment byaisucces'sionf charges and` discharges of the type described above@ ;'-In':ge neral,v thefcap'aci'ty of 'nickeloadnjium-'batteries of the." type. Hdescribed,- above and compo'sed.- opposite polarity electrode plates l of substantially the sane thick ness' is limitedby the=capacityr fthe-active material-of thelipositive k.electrode plates "becais' relativly 'lar`ger amount mi; .the frequiredvfnegative Y elec rode 'm't -iaI l'is present ineach negative plate. of suchbattery i I-n a'ccordance'with tl1einv'entiori, theisin'te'r'ed nickel particlel sheet formation, -used-for 'making v nickelad miumi battery plates of. Opposite 4polarity r'in" the'` nier4 described above, are.. sized for thickness#andy group of thicker. sheetformations are segregated 'fronithe' grop offsmewhatthinnerv sheetforniaitionsfprodue b the sintering'operation; and thegroup `-or groups-o the segfA regatedi thickery -sheet formations 4ar usediforrfmig positive 'electrodes while the 'groups' ofisegregated thinner sheet formations Vare used for :formingthe'negtivelc5 trodes.n tAfter completing the factivatin'fthef'grops of segregated positivev thicker sheetfrmatins-aiid lof the-groups :of: segregated neg'at `i' ve'=thii1r`1er sleeffoi'na tions .bylfthe series o'f treatment steps"r described' ab''e "f each of the two groups of sheet fo-r'atio'risis subjeced-t tiallylthe-'sa'me thickness with the'ne'gaivebat't ry-'plate formationsleb'eing 1 either lof the -saine "thikne'ssfsu'ch .025,5 orslightly thinner than-*the po'sitive 'electrode sheet sterone are placed between adjacent sheet formations. The drying is carried on at temperatures such a`s 80,9 C. or less until they reach constantweight. In this condition, they are ready to be cut into battery plate sections for assembly into batteries. 1:

In the next treatment, step 12, the formed hat sheet formations are cut substantially along the center of their narrow compacted separating zones 55 into the separated individual electrode sections 58. Each electrode section 58 (Figs. 6 and 7) has a narrow highly compacted vthin edge region 55 bordering the relatively largefbody area of each plate section having the desired full thickness and with the pores thereof filled to the desired extent with the active positive and negative electrode` materials, respectively, as described above. Y

AIn the next 13th step, the thin edges of each separated plate section 58 (Figs. 7, 8) are coated ortreated with a coating or cement material which binds anyl loose particles of the edge formation of such plate section and also provides an insulating coating enclosure around any sharp ends of the Wire mesh exposed by the cutting operation. By this procedure, there are avoided uncontrollable and disturbing difliculties encountered in the past resulting in unpredictable short circuits between opposite -polarity electrode plates of the batteries formed of activated vpositive and negative electrode plates, which diiculties developed in prior art sintered plate nickelcadmium batteries usually in the initial operation stages.

Such uncontrollable diilculties are partially overcome bythe fact that before subjection to the loading and activatingv sequences, each porous sheet formation is firmly compacted along its separation zones 55 (Fig. 5). As a result, the substantially solid and almost 100% dense separation zones 55 of each loaded and activated sheet formation contains only a minimum of particles that are liable to become loosened when cutting the large sheet formation into the electrode sub-sections 58. By additionally providing each highly compacted cut edge region 55 of each electrode sheet section 58 with a cementitions insulating coating enclosure, all loose particles-of such edge region are rmly bound in place. In addition, all ends and edges of cut wires of the backing mesh 53 is likewise enclosed in a protective enclosure which suppresses any tendency of such cutg wire ,ends from penetrating a separator formation separating the edge-.region of one electrode from the next adjacent electrode of opposite polarity and thereby establish a short circuiting bridge therebetween.

Any alkaliresistant cement or paint may be used for such edge coating. Among suitable coating materials are any of the known alkali resistant coating compounds of. styrene, styrenated oils, styrenated synthetic resins which are commercially available on the market. Also, aqueous dispersions of vinyl chloride vinylidene chloride polymer, vinyl acetate powder dispersed in glycols and polyglycols and water, apolyethylene solution in aromatic, hydrocarbons, and like cementitious coating material.

Fig. S-A shows in cross-section a compacted thin edge portion 55 of an electrode plate 58 to which a thin coating layer 55-2 of such cementitlous coating material has been applied to the entire periphery of such electrode plate 58. Fig. 8 shows a thick protective layer 55-1 of alkali resistant plastic material applied or secured to the thin compacted edge portion 55 of such electrode plate 58 along its entire periphery so that each electrode plate has along its compacted edge region 55 substantially the same thickness as its main lelectrode region bounded thereby. The thick protective layer 55-1 may be formed of suitable alkali resistant plastic or resinous film material, made in the forni of a channel formation and secured to the thin edge region 550i the electrode plate 58, Yeither-by a cement, such as cemcntitious coating compound of styrene, or the like, or by heat sealing the protective layer 55-1 to the under- 10 lying portions of the'edge region 55. Any alkali resistant thermoplastic '.lm' material may be usedfor the vprotective layer 55-1, such as polyethylene, polyvinylchloride and similar thermoplastic film material. n

In the next 14th and last step, each electrode plate section 58 isy provided with an electrode lead 66.(Fig. 8), formed of a strip of nickel sheet material affixed, as by welding, to the compacted terminal portion 59 of the electrode section 58 which has almost 100% density and permits ready and firm electric welding of a nickel electrode tab 66 thereto. Y

In accordance with another phase of the invention the large multi-section sheet formations 54, such as shown in Fig. S-after fullyloading, activating and siz'- ing in the manner described above, and before cutting them into individual electrode plate sections SS--have applied to their compacted separation regions 55 and their edge regions 57 an clectrically'insulating plastic or resinous protective lm formation so as to .assure that when cutting the sheet formation into separateelcctrode sections 58 along-their separation 'zones 55,' the cut edges of each electrode sheet section 58 will be provided with an electrically insulating coating enclosure for preventing loosening of any powder particles thereof. In addition, after cutting, the edges of each so previously coated sheet edge formation may be further heated or coated to assure that all ends of the wire mesh exposed along the edges by the cutting operation are covered'by a llm of resin or plastic material adhering thereto for preventing development of azshort circuiting bridge between adjacent opposite polarity electrodes of the battery.

By the series of procedures such as described above, there are thus prepared sets'fof positive electrode plate sections 58 and sets of negative electrode plate Sections 58, each section having an electrode tab 66, suitable for assembling therefrom a' battery sub-assembly such as shown at 30 in Figs. l to 3.

In such plate sub-assemblies, the alternate electrode plates 58 of opposite polarity must be separated from each other in a reliable manner by an insulating separator which permits substantially unmpeded electrolytic conduction through the liquid electrolyte placed between adjacent plates while suppressing the possibility of the development of any formations which tend to form a short circuiting bridge between adjacent electrode plate portions of opposite polarity, or in general, preventing s possibility of any partial `or lfull short circuit between According to a phase of the invention disclosed herein, an effective separator for such battery electrodepl'ates is provided by a continuous thin electrolysis pervious film with the film backed on its opposite sides with a fabric layer of alkali resistantthreads or filaments.

Referring to Figs. 10 and 11, the battery assembly v30 has adjacent battery electrode plates 58 of opposite polarityseparated by adjacent sections 71 of' a separator formation of the invention. The separator formation'71 consists of a central lm 72 backed on opposite sides by a'layer of fabric 73. Suitable materials for the elec# trolysis pervious separator lm 72 are lms of regenerated cellulose (cellophane) without plasticizer and similar films of regenerated nitro-cellulose and of organic esters and ethers of cellulose which may be partially saponied, such as cellulose acetate and ethyl cellulose and also films of vinyl alcohol polymer, all without plasticizer. Also, microporous lms which are resistant to alkali solutions and permit electrolytic action through the pores, such as films produced by forming a iilm out of polyvinyl chloride dispersed and/or dissolved in a solvent and hav ing admixed thereto dissolvable additions, such as starch or dextrin, and after driving o the solvent, thestarc'h or dextrin additions thereof are removed, for instance, by a treatment with sulfuric acid solution at 90 'to 100 Y C'. or by such sulfuric acid' treatment preceded by .al treat# ment with a caustic alkali.

desired separatorformation'71 is prepared by assembling long strips of thedesiredcontinuous.thin centrallm-72 between two .longfabric strips' 73 to'provide-a composite 'separator formation of substantial length and the required i width-'. 'The,opposite polarity.electrodeplates 58 are then assembledciirV superposedrelation while folding the-'separator formation 7'1' in Yzig zag fashion-(Fig. -1l).in oppositedirection around adjacent electrode plates 58. Y The composite separator formation 71 is made of -a width r labout'Mf-to %;inch: greater thanthe height oftheelecvnode-pilates 58` (Fig. 9) so'that lthe-apjgterand lower'border 1egions,71'-1of theseparatorformation 71 overlap! and project beyond the upper and lower edges of the inrdlvid-V ual Aopposite polarity battery'plates158 of the battery I In, assembling Valternate positive I'andxnegative electrode plates '.-58 linto a sub-assembly 30;'(Figs. A9 and-10), the positive relectrode plates are so arrayed that their out- -wardly 'proie'cting'electrode tabs 66 are aligned insuperapose'drelation along'one one side "of the battery assembly ,whilethe electrdeltabs 66; of the arrayed-electrode plates of opposite polarityxare similarly arrayed in superposed 'relation along -the opposite side ofthe assembly. a; After thus `assembling the yelectrodeV plateslof opposite polarity into .a :battery sub-assemblyw'ith lsuccessive sections of the composite separator formation'71 folded inzig'zagf fashion between adjacent electrode plates-58, andfwith'-thefuppernand the-lowerborders 71-1 ofthe separator-formation 1,71 projecting beyond the upper borders ofthe alignedv superposed opposite polarity plateV formations 58 -.the subassembly is completed' by wind- ,fing around apart of the length of a pair of its opposite edge regions, 'such as the" upper and lower edges, a fas- Y tening strip 75;- of'alkali' resistant film material and fasten- Y V`ing theouter'endoflthe stripto anunderlying-turnof the strip as by aceine'nt o1'- by heat sealing (-Figsl9, 10).

Any alkali resistant film Vmaterial or fabric of the type described above ma'ygbe used for the fastening strip-75.

order; .to` properly distribute thel forcesicxerted byV fasteningstrip 751 onY the opposite edge 'regions oftthe platel assembly, such as the upper and lower edgesfofthe its ,lside1borderfs borderinglthe fastening 'stip 7S maybe Y provided -with slightly, raised. outward shoulders for .'givingthe yoke member 75f`1substantial= stiffness and pre` tftnlbcndllrgfthereof.- The Ayoke memberl7511-th`us rests against the.,-;overlapping edge regions v. .of 'f the 'separator 4se :(ti,o ns .71. projecting above the upperV and'lower edges ofthc individual, electrode plates-SS-of'the plate assembly The Voverlapping. edge regions :of the separatorseei tions 71-.are,thus';interposed between ktheedge'sno'f fthe electrode plates 58', ahd'tlieV opposite yoke members 754 Vwhich together withthe-fast'ening strip-75 .form vthe 'fastfenng structure byjwhicli the ,electrodefi'plates .'58 are fastenedintqa self-Supporting electrode 'assemblyn 'Depending lupon the sizeof the electrode plate arca', several similarfastening;'structures 75, 75.-1 are 7provided along snacedepcrtonsof oppositeedge 'regions joffthe plate' as;-

fatz

By wayof example, =and without thereby limiting the scope of the inventiong'therewill bernow described 1one form of a composite'j separator formation actually 5`used. on a production basisifor manufacturing batteries'of-the invention. A thin film of regenerated cellulose (cellophane) about .0010 'to '.0016 inch thick is used as a con;v tinuous tilm 72 of the Yseparator formation 71. The thin cellophane film is'backed on -both sides by ashee'fbf woven nylon fabric 73, each' aboutfOOl to .007 inch thick. Good results are obtained-with fabric layers of .O0-'tto .0055 inch thick giving a composite separator formation of -an overall thickness of about .010 to .0l4`inch thiclenessun. A.m1-if A continuousfflm `72 of cellophane of similar Jalkali resistant and electrolysis `pervious film' materialhas been Y foundto be ideal as a continuous film barrier which-per.- mits 'relatively free 4electrolytic action through Ythe alkali velectrolyte permeating all free spaces between opposite charged, 'gas 4will develop in the space betweenthe adjacent electrodes andlthe electrolyte l'ling 'the same. TheA gas evolution at the electrodefaces tends to tear the thin barrier-of vcellophane orlikersuitable material: Airlincrease in the thickness of-the'continuousfilmfbarrier vso aslto renderit resistant lto tearing by the gas evolution', Lresults in' undesirable'inrease'of the internal impedance of the batter-y cell andimpairs itsusefulness. AByeolnbining suchl thinV continuous --barrier film with strong but vhighly porous backingfabric layer on' both sides of the t .continuous-barrier tilm, the invention provides a-f oolpi'ocp'fr 'batterywith very low internal-impedanewhich has a very long yuseful lifezunder suppression of erratic -short circuits 'between opposite polarity electrodes'. 'Y -f ln other words, the provision of the'strongfabric back- -ing 73 along-'each side'of .the A'thin Acontinuous lilrn barrier `72 assures thatthe-'elements ofthe-film bai'rier'rernain in' their position notwithstanding the evolution of4 gases at the electrode Vsurfacesv and prevents rupture of the film by the gases evolved during the charge. On the other ihand, it'wa's foundlfthaStsincerthe backing fabric layers 73 .of'th'e'sseparator formation have all their pores'filled-'with Ytheelectrolyte,they do not'materially increase thfint'trial impedance ofthe battery."- f -l .:'It has also .beefond that'after a relatively shofpe- '.riod ofopera'tin, the''ontinuous separator film of mate- -rial such asie'g'en'erated celluloseZdeterioratesandrhasna 'tendency to fall apart; By backingv up :such continuous electrolysis pervious tilm' formation with strong ,fabric 'layers 73, the vparticles Vofthedeterioratingfilm bla, 72, suchas cellophane lbeome matted vbetweenthe Vfabrie'-lay ersI 73 'and'theyare retainedin position as'afco'lt'in'uous"-b'a-rri'erV 72 between the'adjacent electrodeplates4 'of dopposite polarity. f y Y Y iS-uch :continuous flril barrier, retained between Y alkali 're'sistantistrong porous fabric-'layers in its operative posi,- tion,'notwithstanding the` deterioration of the filmfmakes Qitfalso possibletolretanain nickel-cadmium battery of the inven'tio1i',a ,large percentage-of theelectric charge overta longperiol of time,A such as one-halfrto one year :and'more atj roomtemp crature.; This is another putstandingadtvanta-ge of thebatteries of `the inven`tion.-1v

Battery cells provided .with such separatorsof ftheii'nyentionwill operate for long periods in inverted -position', fi. e. with thetopwall 15 facing vertically Ydownward,with 'all excessfelectrolyte till-ing the normallyemp-ty casing `space overlying thedownwardly facing top Vwall. Y Thisfde Y .7 -the electrode plates substantially thesame quantity le'c 13 trolyte whether the battery cell is held in its normal position shown in Figs. 1, 2, or in an inverted position.

It should be noted that when using wire gauze for forming with sintered nickel powder thin porous electrode plates of the type described above, the wire gauze has an average thickness much greater than the wire out of which it is formed. Thus, in case of wire gauze mesh 20 X 2O x .007, formed of wire .007 inch thick, the average thickness of the gauze is about .014 to .018 or even .O20 inch. When forming with such wire gauze sintered powder formations .025 inch thick, the gauze is usually not centrally positioned within the powder layer but along one of the faces of the powder layer.

Below will be described a procedure which makes it possible to center such continuous metallic backing structure within the sintered powder layer. The wire gauze is subjected to a calendering formation wherein its protruding regions are attened to the thickness of the individual wires such as .007 inch for the particular gauze here considered. Such calendering operation gives the crossing wires a stronger interlocking engagement at the crossover regions. Such calendered gauze may have also struck out of its surface bent wire tines at spaced area portions thereof to provide spacer legs which support the gauze spaced in the center of thepowder layer placed in the mold, while the nickel powder is deposited on the bottom surface of the mold cavity for producing the sintered powder sheet formations. Such tines or spacer. legs may also be pro# vided on continuous perforated metallic backing sheets used in place of wire gauze, and also in the cases where a continuous non-perforated sheet of nickel is used for sintering to both side surfaces thereof thin layers of nickel powder. Thin calendered wire gauze of the type described above made of wire .007 to .005 inch thick, and calendered to a thickness of .007 to .O inch makes it also possible to produce electrode plates of the invention having a thickness of only .O inch.

After completing the sub-assembly 30 of electrode plates of alternate polarity with interposed separator formations 71 and held together by a fastener sheet 75, in the manner described above (Figs. 9 to ll), with their aligned two sets of electrode tabs 66 of opposite polarity arrayed near the opposite side edge region of the battery assembly (Fig. 9), the arrayed electrode tabs 66 are bent in the manner indicated at 32 in Fig. 2 and their upper end portions are clamped to each other in superposed relation within the inner U-shaped ear members 26 of the two terminal member Shanks 21 of the battery top 660i opposite polarity so held within the U-shaped ear members of the terminal members 21 are then welded to each other and to the ears 22 of the terminal members 21 as by an electric welding operation to provide a good mechanical and electrical connection therebetween of the opposite polarity terminal tabs. When the two sets of electrode tabs 66 are so arrayed in superposed rela tion and affixed with their outer ends 31, 32 to the U- shaped inward ear members of the two afxed outer battery terminal members 21 (Figs. l, 2), they provide in their aggregate relatively stiff interconnections between the rigid top wall of the battery cell casing and the electrode assembly for holding the electrode assembly 30 inits downward operative position within the cell casing walls 11, 12 such as shown in Figs. l and 2. Such relatively stit interconnection between the battery assembly 30 and the top wallA 15 of the battery is obtained notwithstanding the fact that the individual terminal tabs 66 of the individual electrode plates 58 of the assembly 30 have only little stiffness and may individually be easily bent. By way of example, the individual terminal tabs 66 of a battery assembly of the type described above may be formed of sheet material of nickel, about .007 to .010 inch thick. When assembled in superposed arrayed relation and connected to the inner U-shaped con-A nector ears 26 of the opposite battery terminal members 14 21 held affixed withinv the top plate 15; of the battery cell, the so arrayed electrode tab connectors 31, 32 of the electrode assembly 30 provide relatively stii bracing connections to the top wall 15 of the battery cell sutiicient for holding the battery assembly 30 in its inward posiv tion within the casing walls 11, 12 whenthe battery top wall 15 is aflixed within the upper opening thereof.

As seen in Figs. 1 and 2, the battery top or cover wall 15 of the battery cell is relatively rigid land is provided with a generally rectangular border portion 16 arranged to fit within the interior of the adjoiningfrend of the battery cell casing walls 11, 12. The interiitting surfaces of the top wall 15 and cell casing walls vf11, 12 are hermetically joined to each other as by ai suitable alkali resistant cement, such as cementitious compounds of-SKY rene, styrenated oils, styrenated synthetic resins ,which are commercially available on the marketQ Alternatively,

the interiitting walls may be atixed to`each other by heat sealing. i v

The electrolyte within the interior of `the cell casing 11-1 is maintained at a level of aboutllt to inch above the upper level of the electrode plates of the electrode vassembly 30 positioned in the inner part of the battery cell casing 11-2. f

The top wall 15 of the battery is also provided with a venting and iilling structure to permit gases evolved in the interior of the cell casing 11-2 to be discharged before they develop excessive pressure and also to permit re plenishing of the electrolyte within the cell casing.

In the form shown, the top wall of th` battery Acasing has at its center a vent and filling opening 17. The top wall opening 17 is shown closed by a yclosure member 81 of alkaline resistant metal, to wit, nickel, having at its lower end a threaded portion 82 arrangfd to threadedly' engage the threaded walls of the top wall opening 17. The closure member 81 is shown provided with an intermediate portion thereof with a sealing Harige 83 arranged to overlie and clamp an underlying sealing washer 84 of neoprene, for instance, by means of which the closure member seals o the top wall opening 17, when the closure member is in its sealing position. (Figs. 1, 1-A, 2.) The outer end of the closure member 81V provided with a head 85 having on its exterior a slit so that its threaded inner end 82 may be readily screwed in fand out, as by a screw driver, from its threaded engagement with the threaded top wall hole 17.

The outer part of the closure member 81 bounded by its outer head 85 and intermediate closure flange 83 is enclosed with a tubular sealing sleeve member 86.0f yieldable elastic rubber-like material. The closure mem-` ber 81 is provided with an axially downwardly extending vent passage or bore 87 having at its top a lateral Outlet opening 88 which is normally maintained sealed by the elastic pressure of the sealing sleeve 86. The vent pasv sage 87 and its sealing sleeve 86 are so designed that under excessive gas pressure developed in the interior of the sealed cell casing walls 11, 12, the gases will lift the Sealing sleeve 86 from the vent outlet opening 88 and permit gases to escape therethrough. y

The top wall 15 is provided with an outwardly extend ing tubular wall portion 18 of the top wall 15 surrounding the outer part of the closure member 18 and serving as a well or retainer structure for retaining electrolyte dis'- charged through the vent opening passage 87 and 88 with the gases expelled therethrough. n

The vent opening region 17 of the top wall 15 is also provided with an inwardly extending tubular spray .Ybae structure 19 for suppressing spraying of electrolyte into the top wall opening 17 by gases evolved during .the charging operation. In the form shown, the. tubular spray bale 19 terminates at its lower end slightly above the upper edge of the battery plate assembly 30 and serves as a stop against outward movement of the battery assem'- bly when it is accelerated by impactforces from its in ward position towards the top wall 15; Y f

Y. fjf'fhe` lower-edg'ef-of the'tubular'sprayrbalie wall 19 'of theto'p wall-15 terrninat'esbelow'the level 41 of the electrolyte Within the batterycell casing, thereby sealing loiffthe lower'edge' of the tubular spray bafie '19 against direct entry of sprayed electrolyte, since the lower inner edgev oft/the tubular baffle spray'19'overlies the` region of the battery assembly' which is enclosed-at thetop by the fastening strip-'l5 and also the yoke member Gases evolved between the adjacent electrode plates of thebattery assembly will thus befdischarged into theupperspaceof lthe.battery-compartment outside the "spaelenclos'edwithin'the spraybaifie19 'and any electrolyissp'r'ayed by such gases-in upward direction will be deilected by thetubular baffle 19v away from the .top -wall wenn 1.1. Y. A Y f i l The Vga'se's so discharged into' theupperspaceof Athe .batt'e'i'yca'sing wallsV 11, '12 surrounding thek tubular spray l'baille l l19 may ow therefromv through i lateral i openings 89 provided in the tubular bafe walls 19 nearthe'upper region thereof so that the gases may passtherethrough and i tubular' well wall 18, Vits outertside. walls areshap'ed vto Y providev a` defiectin'gV `channel 'SM .whichcontines the out'- vflowinigfelectrlyte to a 'downwardly flowing direction" and suppresses vleakage -of electrolyte toward the surrounding topffsur-face portions-of the top wallf 15 of the battery. Batteries Vofi the invention ofthe-ty'pe describ'edf'aboye arecharacteriied by very highdis'chargefcapeity under shortcircuitf conditions and will :operate during a very long-'useful life`under a varie'tyl of= adverse conditions =Which1would irfnpa'ir the operation of 'other batteriesl By wy'if-'example, and without thereby limiting the scope 'of the inventionythere are given in Figs, ll-A', Vll-l?,"and

il1Z-C;cur`ves-:showing 'typical dischargecharacteristics of T one form of a battery based on the principlesof thein- Yntionc'l'lhespecic batteryhad 8 positive lelectrode plates-and 7ln'egative electrode plates eachplatel being Ylfinch wide,'2%- linches' long'and '.025 inchthick. Fig'.

Y hiv-A showslthe discharge-'conditions of such 'battery cell 1;'

forliaconstantcurrent 'discharge ofV =10 amperes, the dis'- diarge'coriditionslduring the first ten seconds being vshown on an enlargedfscale in an auxiliary'curve portion to `the'rght of- Fig. 11. `Fig.'l itl-B 'and Fig. 114C show'cor'- respondii'gdischarge'V characteristics for" dischargesV with aeonstantcurrentat the'rfate' of-30 amperes' and 50 am# peres,.res"pect'ively.= f Y .ZrsAccording to a'further phase of the'invent'ion, 'a battery formed of a plurality of battery cells-'eachv generally rec' tangulari."'cell. casing, isfso' arranged as to cause any electrolyteexpelledfromf the interior of th'eleell casing to -be detiectedfromlthe top surface of the' cell vcasing toward thev exterior fof the-sidewallsof theadjacent cell casing xhichLai'e-lso shapedas to Y.forni c'o'njoi'ntlyV deilecting channels along which electrolyte: reaching'thesarn'efv is d'eecteddownwardly'an'd disch' rg'edthrou'gh -the bottom "ofzthefbatteryassembly. 1

-a.1`igs'.;fl2,.l3' and-'l3-A show onefform cell assemblyeexemplifying the invention.

of a "battery 'In the V'form shawn; the;battery-comprises'an array of two rows of :4 laatteryzcellsV :101with .thea't' cellfcasing 11-0 held`ad` jacent to eachother. kThe terminal posts 21 of adjacent battery ells; 10 are shown interconnected "by "connector Vor;jumper-.members 24'-5 to provide series connections f between all the cells 10 ofthe battery'assembly, The

'516 individual jumpers 24-5 may bev formed t'ifnetalV having sealing holes'seated onthe upper threadedportions of the 'respective terminal r'nerr'ibers'Y 21 and held 'aixed in-position by the fastening nut'rnernbers r2,4-'1

` -The arrayed battery cells 10 are held in' their positions shown by a' batterycasing generallyrdesignated 85 of rectangular shape having a bottom wall 86,*two' side walls 87' and two end' walls 88; Gases evolved in the individual cellsfduring charging -subjectthe individual cellV casing walls to relatively large internal expandedfo'rcesl` zAs a result, when gas is generated in the'individual;cellsf 1Q, such battery cell assembly exerts-on the side Walls'of'th'e batteryg'casingfSS cumulative expanding which 'subjects the-1 walls of the battery casing 85 to greatj'sfranstjrTo retai'n the'ass'embled cells of the battery'in their Iarrayed.

positions, the battery casin'g385 is "made ofv strongA sheet t metal such as steel.- To prevent suchsheet' metal vwalls-of fao entitled "fViny-l g-plastisol compounding-f 'composition is applied-to the sheet -metal'casing ,85 by dip'- the battery casing-'85 from corroding lwhenV exposedzto alkaline electrolytejtheslieet material of the batterynasing'hashi'ghly bonded orunited thereto a-'coating layer' of alkaline resistant coating materiali.v After extended search'- ing,-'it -was found'that V'such highly bonded alkali-resistant coating maybe formed on the sheet material of such bat,- -tery casing'SS out of a dispersion of yinyl resins in `liquid plasticizers or plastisols which are described in Modern Plastics, volume 27, fpage Vlll, November, 1949,a`rticle The coating pin-g or 'pouring whereupon the' applied coating composi tionjislcur'ed by heating atan elevated-te'rnperature o'f 35:() to 37.5 F4170 m-19o"C-.`).'; g l 1'- -According to'y the invention, rthe vside walls of theindi yvlualv cell-'fcasing-llhavevk their upper :outer surface re'gior'lsadjoiningl Ythe cell top wall 15 V recessed at 1114 relativel'yto thelhottorri4 surfaceregiohs l1-5 fof the' cell casings, so that adjacentcell` "casing walls forntfdown` -wardly extending defiecting channels 11-'6' (Fig. '12) Lalong which electrolyteleavin-g the'well'18- on the top'lS sofa cell shall ilow into the vdeflecting channels l11-'13.between the upper regions of thev cell casing sidewalls and therefrom towardsv the bottom -of' the-"bttery asse'mbly. ""In addition, each lbattery cell casing 1'1-0 is rounded' at its corners 123 (see Fig. 3) 'so' -that lwhenkadjacent'cell casing X11-dare assembledadjacent to eachother within the battery casing" 8'5, (Fig. v13.)-'the lv rounded corner regions 12-3 ofadjacent -cell easings form downwardly extending corner channels-'1241*along whichelectrolyte 'deected by-jthe-side'wall channelsl'I- shallilow through the `corner channels towards *thebottom Yof 'the lbattery casing 85; The bottom wall' 86"-of the battery casing 85 has discharge'openingsfSG-l aligned'with 'the bottomends Y'of thecorner channels V12f4between the celli'casing '11-0'gfor discharging through' these openings 86-'1 liquid-*flowing ldowrm'ardlyl through" the!" orner channels. g Battery cell casings' arrayed'finV the manner c lescribefd` above, `when' assembled yin side by sidel relation'WithinA a battery, permit ready washing orf'of, any electrolyte from the exterior thereof.' This may bey done'v by 4applying a" hose of clean water and discharging'it valong the topi-of 'thebattery assemblyl (Fig.l l2).- The 'so dischargedwiai terwashes electrolyte present on exterior'surface portions of -batterycell casings andthe :washwater'with itsi' tentswill ow downwardly *along thefchannehforrhations ,11;-6-between-thev cell casing sidef walls'andfthecorner `channels l124 between -adjacentcell 'casirigsg f and be Ldisf 'charged through the Vdischarge openings 86-1'of the botl tom wall 86 of the battery eas'ingsS. f According tothe invention, a' multi-cell batteryV casing is arranged and p'royided with a simplified way' for retain-V ing the assembled'array'of battery cellrcasings' withinthe battery casing while'V permitting :exchange 'or removal `of onel or moreof the battery cellsyvitha minimum of'eifort. "'Refer'ringtofFigsl l2, 131andl3-Ayshowingone'form of a battery casing of the invention, the extended side walls 87 of the battery casing 85 are provided at their upper regions with an inwardly bent barrier wall 87-1 overlying the adjacent portions of the array of battery cells 1G held within the casing 85. The extreme edge of the inwardly bent barrier wall 87 is bent downwardly at 87-2 (Figs. l3-A) to give it the shape of a downwardly facing channel-like barrier. The upper barrier wall 87-1 of each casing side wall $7 is cut away along an intermediate region 37-3 thereof to provide a gate region through which one or two cells positioned within the casing S5 adjacent the gate region 87-3 may be freely lifted upwardly without interference by the channel barrier wall iii-1 overlying the top wail regions or other battery cells lll held within the casing 85.

The arrayed battery cells 1li are held clamped in the position shown against the bottom wall 35 of the batteriI casing S5 by placing between the overlying barrier wall S-l of each casing side wall 37 and the underlying cell wall regions a wedge structure 91, 92. The wedge struc ture 9i, 92 shown is formed of two solid longitudinal wedge members which when assembled adjacent to each other along a slightly inclined aoutting surface 93, provides along their outer surfaces two parallel abutting surfaces which are clamped against the underlying top wall regions of the battery cells l) and against the overlying barrier wall S-l or" the battery casing or holding the array of battery cells affixed within their inner positions in the battery casing 85. By longitudinally shifting or pushing one of the barrier members 91, 92 in a direction generaliy parallel to the side walls S7 of the battery casing S5, the wedging enfagement between the two wedge members 9i, 92 may be readily loosened, whereupon the two wedge members may be freely removed from their locking engagement under the channel barriers 8'7-1 of the battery casing S5.

With the foregoing arrangement, desired battery cell 15 may be readily removed from its position within the battery casing 85 as follows:

The wedge members 91, 92 are removed in the manner described above, thereby freeing the individual battery cells for upward movement within the battery casing 85. The battery cells which are to be removed are thereupon disconnected from the adjacent cells. This may be readily done by unscrewing the fastening nuts 24-1 and removing the connector jumpers 81 from the terminal members 21 of the individual battery cells 10 which are to be removed including one of the two battery cells positioned adjacent the gate region 37-3 of each side wall. Thereupon, the freed battery cell 1li at the gate region 83 is lifted from the battery casing 8S. Thereafter, as many other battery cells as desired may be similarly moved within the interior of the battery casing to the gate region 87-3 of the side wall barrier 87-1 and similarly lifted and removed from the battery casing 85.

By reversing the procedure described above, the removed battery cells 1i) or substitute similar battery cells may be reinserted into their assembled positions within the battery casing 85, and also after so assembling them, the arrayed assembly of battery cells may be readily locked in their positions by insertion of the wcdging members 9i, 92 through the open ends of the locking barrier 87-2 as seen in Figs. l3-A.

The features and principles underlying the invention described above in connection with specific exemplication will suggest to those skilled in the art many other modifications thereof. It is accordingly desired that the appended claims shall not be linited to any specic features or details shown and described in connection with the exemplirications thereof.

I claim:

l. In an electric battery, a plurality of battery cells having generally rectangular cell casings with the side walls of adjacent cell casings abutting each other over Cir 18 at least parts of their areas, said abutting side walls be ing recessed along their facing upper regions to provide between extended adjacent facing side wall areas discharge passages through which liquid overflowing the top regions of said cells will flow downwardly and laterally to the edges of said side walls between adjacent side walls, adjacent side walls of said casings being also spaced along downwardly extending corner wall regions to provide between them discharge channels for discharging liquid flowing through said passages beyond the bottom of said cell casings, the top wall of each cell having an opening through which electrolyte liquid may ow between the interior of said casing and the exterior of said top wall, said top wall having an upwardly projecting hollow retainer structure for retaining liquid overowing through said opening, upper wall portions of said retainer structure being shaped for discharging liquid tending to overow said retainer structure into at least one of said discharge passages.

2. In an electric battery a plurality of battery cells having generally rectangular cell casings with the side walls of adjacent cell casings abutting each other over at least parts of their areas, said abutting side walls being recessed along their facing upper regions to provide between extended adjacent facing side wall areas discharge passages through which liquid overflowing the top regions of said cells will iiow downwardly and laterally to the edges of said side walls between adjacent side walls, adjacent side walls of said casings being also spaced along downwardly extending corner wall regions to provide between them discharge channels for discharging liquid owing through said passages beyond the bottom of said cell casings, the top wall of each cell having an opening through which electrolyte liquid may ow between the interior of said casing and the exterior of said top wall, said top wall having an upwardly projecting hollow retainer structure for retaining liquid overflowing through said opening, upper wall portions of said retainer structure being recessed for discharging liquid tending to overow said retainer structure into at least one of said discharge passages.

3. In an electric battery, a plurality of battery cells having generally rectangular cell casings arrayed in at least one row with the side walls adjacent casings abutting each other over at least parts of their areas, a generally rectangular battery casing having two sets of opposite side walls bounding a casing space for holding in their positions said array of battery cells with at least one row of cells arrayed adjacent one set of opposite side walls, the top regions of said one set of opposite side Walls having inwardly projecting opposite barrier wall portions overlying top wall regions of the cells arrayed adjacent said side walls, each of said barrier portions having a length shorter than the side wall from which it projects to provide an upwardly opening gate portion through which at least one cell casing arrayed along its side wall may be lifted upwardly and removed from said casing and an elongated locking structure removably clamped between each of said opposite barrier portions and the underlying wall regions of the arrayed cells for holding said cells fixed in said casing, each elongated locking structure having a length greater than the barrier portions engaged thereby so as to prevent removal of any battery cell from said casing while said locking structure is in its clamped position.

4. In an electric battery as claimed in claim 3, said locking structure being insertable into and removable from its clamping position by a movement in a direction parallel to the side wall along which it is clamped.

5. In an electric battery as claimed in claim 3, said locking structure being insertable into and removable from its clamping position by a movement in a direction parallel to the side wall along which it is clamped, said locking structure having two adjacent elongated wedge members provided with elongated parallel outer surfaces constituting the outer surfaces of said locking 926,649 Gardiner et al. June 29, 1909 structure which are in clamping engagement with said 1,152,246 Walker Aug. 31, 1915 barrier member and the underlying Wall portions of said 1,290,487 Melia Jan. 7, 1919 cells, the two Wedge members of each locking structure 1,514,670 Melchior Nov. 11, 1924 being movable relativerto each other in the direction of 5 1,978,779 Barton Oct. 30, 1934 their length Valong elongated facing contacting surfaces 2,136,749 Martino Nov.' l5, 1938 inclined under a slight angle relatively to their elongated 2,186,148 Raney Jan. 9, 1940 outer surfaces. 2,385,127 Carlile Sept. 18, 1945 References Cited in the le of this patent FOREIGN PATENTS UNITED STATES PATENTS 729,550 Condict June 2, 1903 481,891 Great Britain Mar. 1s, 1938'y 

1. IN AN ELECTRIC BATTERY, A PLURALITY OF BATTERY CELLS HAVING GENERALLY RECTANGULAR CELL CASINGS WITH THE SIDE WALLS OF ADJACENT CELL CASING ABUTTING EACH OTHER OVER AT LEAST PARTS OF THEIR AREAS, SAID ABUTTING SIDE WALLS BEING RECESSED ALONG THEIR FACING UPPER REGIONS TO PROVIDE BETWEEN EXTENDED ADJACENT FACING SIDE WALL AREAS DISCHARGE PASSAGES THROUGH WHICH LIQUID OVERFLOWING THE TOP REGIONS OF SAID CELLS WILL FLOW DOWNWARDLY AND LATERALLY TO THE EDGES OF SAID SIDE WALLS BETWEEN ADJACENT SIDE WALLS, ADJACENT SIDE WALLS OF SAID CASINGS BEING ALSO SPACED ALONG DOWNWARDLY EXTENDING CORNER WALL REGIONS TO PROVIDE BETWEEN THEM DISCHARGE CHANNELS FOR DISCHARGING LIQUID FLOWING THROUGH SAID PASSAGE BEYOND THE BOTTOM OF SAID CELL CASINGS, THE TOP WALL OF EACH CELL HAVING AN OPENING THROUGH WHICH ELECTROLYTE LIQUID MAY FLOW BETWEEN THE INTERIOR OF SAID CASING AND THE EXTERIOR OF SAID TOP WALL, SAID TOP WALL HAVING AN UPWARDLY PROJECTING HOLLOW RETAINER STRUCTURE FOR RETAINING LIQUID OVERFLOWING THROUGH SAID OPENING, UPPER WALL PORTIONS OF SAID RETAINER STRUCTURE BEING SHAPED FOR DISCHARGING LIQUID TENDING TO OVERFLOW SAID RETAINER STRUCTURE INTO AT LEAST ONE OF SAID DISCHARGE PASSAGE. 